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futex: futex_wake_op, fix sign_extend32 sign bits 

sign_extend32 counts the sign bit parameter from 0, not from 1.  So we
have to use "11" for 12th bit, not "12".

This mistake means we have not allowed negative op and cmp args since
commit 30d6e0a419 ("futex: Remove duplicated code and fix undefined
behaviour") till now.

Fixes: 30d6e0a419 ("futex: Remove duplicated code and fix undefined behaviour")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <dvhart@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jiri Slaby 2017-11-30 15:35:44 +01:00 committed by Linus Torvalds
parent 51090c5d6d
commit d70ef22892
1 changed files with 2 additions and 2 deletions
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4
kernel/futex.c
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@ -1582,8 +1582,8 @@ static int futex_atomic_op_inuser(unsigned int encoded_op, u32 __user *uaddr)
{
unsigned int op = (encoded_op & 0x70000000) >> 28;
unsigned int cmp = (encoded_op & 0x0f000000) >> 24;
int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 12);
int cmparg = sign_extend32(encoded_op & 0x00000fff, 12);
int oparg = sign_extend32((encoded_op & 0x00fff000) >> 12, 11);
int cmparg = sign_extend32(encoded_op & 0x00000fff, 11);
int oldval, ret;
if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) {